Taper plating serpenting fins



Aug. 2, 1966 A. B. MODINE TAPER FLATING SERPENTINE FINS Filed Jan. 29, 1962 United States Patent O 3,263,313 TAPER PLATING SERPENTINE FINS Arthur B. Medine, 119 11th St., Racine, Wis. Filed Jan. 29, 1962, Ser. No. 169,279 6 Claims. (Cl. 29-157.3)

The invention relates generally to heat exchange structures and more particularly to a heat exchange structure of the serpentine iin type.

Fin structures formed from strips of metal which have been shaped into a serpentine or corrugated configuration have become popular due to the simplicity of constru-ction and adaptation to manufacturing techniques, at :the same time providing an effective heat exchange structure.

The advantages of tapered fin structures and heat transfer devices has `been well known for many years, but the advantages thereof have not been effectively employed due to the difficulties in manufacturing tapered formations in the extremely thin 1in material normally employed in exchanger structures of the type involved, such thickness normally being of the order of ve thousandths of an inch or less. Likewise, while thinner material might be satisfactorily utilized from an efficiency standpoint, fabrication requirements have normally dictated the nature of the materials involved.

Where rolling or other metal processing operations are utilized to achieve variations in fin thickness to provide or at least approach a tapered construction, prod-uction problems multiply as it is exceedingly `difficult to hold close manufacturing tolerances with extremely thin gauge material and in particular to avoid tolerances which become cumulative and necessitate extremely close supervision of the production operations, etc.

The present invention is therefore directed to a novel method of forming a serpentine n structure employing tapered tins, in the practice of which accurate tolerances may be relatively easily maintained without involving a cumulative action, and which may be accomplished in a relatively continuous operation.

Another object of the invention is the production of novel apparatus for selectively plating partially formed iin material whereby each iin element is provided with a plating extending from approximately the central or intermediate portion of the fin to the connecting portions at each side thereof whereby the thickness of each fm element tapers from its outer edge inwardly toward the intermediate portion thereof.

Another object of the invention is the production of a novel tapered n structure which may be suitably constructed, slit, o-r otherwise formed.

Many other objects and advantages of the construction herein shown and described will be obvious to those Skil-led in the art from the disclosure herein given.

In the d-rawings, wherein like reference characters indicate like or corresponding parts:

FIG. 1 is a perspective view of a section of a serpentine fin structure of the type involved;

FIG. 2 is an end elevational view on an enlarged scale of a portion of a serpentine iin structure;

FIG. 3 is a graph illustrating, on a highly enlarged scale, the relative proportions of the original strip of material and plating in a typical n structure;

FIG. 4 is a diagrammatic top plan view of an apparatus for producing the tapered tin structure;

FIG. 5 is a sectional view taken approximately on the line 5--5 of FIG. 4; and

FIG. 6 is an end elevational view, similar to FIG. 2, in single-line schematic form, illustrating por-tions of la fin element following successive operations thereon.

The .present invention generally contemplates the formation of a corrugated fin structure, as for example, from strip material of substantially uniform thickness, following which the structure is selevtively plated, preferably with metal of the same kind as that comprising the strip, to form a heavier plating adjacent the connecting crown portions of the fin structure than at the interconnecting intermediate portions thereof, so that each fin element tapers in thickness from adjacent its crown, or connecting portion with the next adjacent fin, toward its intermediate portion. As the initial corrugating may be done in accordance with current manufacturing techniques with a relatively high degree of accuracy, and as the plating operation may be carefully controlled, normal manufacturing tolerances may be readily achieved, this being due in part to the fact that the taper-forming operati-on may be performed upon material previously fabricated to a corrugated form whereby tolerances in the final structure involved in the plating operation are individual to the respective fin elements and thus not cumulative along the serpentine structure.

Referring to the drawings, and particularly to FIGS. l, 2 and 3, the reference numeral 1 indicates generally a lin structure comprising a strip of material which is suitably formed to provide a plurality of secondary surface n elements 2, connected along their opposite ed-ges, by connecting portions 3i, with the adjacent n elements at each side thereof to form a structure having a serpentine or corrugated cross-sectional configuration.

As illustrated, on a larger scale in FIG. 2, the thickness of the n elements 2` vary from a maximum thickness adjacent the crown or connecting portions 3 to a minimum thickness at the intermediate section o f the intermediate portion of each fin element. Thus, the thickness of the lin element is at a minimum approximately at the line aa and at a maximum approximately at the lines bb.

A typical example of a section of a n element, on a highly enlarged scale, is illustrated in FIG. 3, wherein the the numerals along the abscissa rep-resent units of fin width from the zero center of the flat portion of the lin and the figures along the ordinate represent Jthousandths of an inch.

The particular example illustrated employs thin stock of an initial thickness of .003 and a maximum plated thickness of approximately .0019 adjacent the connecting portions 3 which plating tapers to zero adjacent the center of the thin portion, the particular example illustrated having a slight overlap whereby the inner edge of the plating terminates approximately at 3 at the inner side of the center, referring to the inner side as being that adjacent the inner face of the connecting portion.

In theoretical design, for example, for use in automotive exchangers and the like, the initial strip material may be as light gauge as can be satisfactorily fabricated and handled as a serpentine structure and would normally be about .002, in which case the plating would normally approach a maximum of approximately .001, tapering to zero at the midpoint of the lin. As the dimensions will naturally vary in any given situation, the above figures are not intended to be limiting in nature, and will vary with the ldesign factors of the particular exchangers, as for example, the n spacing, fin width, as well as other factors in the general heat exchanger design. Thus the gures indicated are directed to a fin structure having the approximate proportions illustrated, in which case the flat fin width is approximately seven-sixteenths of an inch. FIG. 3 on the other hand illustrates the fabrication of a iin element embodying .003 stock with a maximum build up of approximately .0019. In the practice of the invention, ns have been fabricated having plating build ups from .003 to 00029.

In fabricating the fin structure, the strip material of uniform thickness is initially formed into a serpentine or corrugated configuration generally corresponding to that illustrated in FIGS. 1 and 2, any suitable apparatus being lCe employed therefor, as for example, by the use of two intermeshed toothed forming rollers similar to meshing gears.

Following suitable formation of the corrugated structure, the latter may be passed through a plating solution wherein the strip receives the desired amount of metal plating.

The plating operation may follow general plating techniques as to the character of the plating solution, plating current and plating times employed, etc., but in addition thereto the present invention enables the utilization of an additional operational factor. As the amount of metal deposited or plated on a surface during the plating operation will vary with the relationship of one particular surface to another surface of the object, as for example, recessed surfaces, etc., the plating being heavier on edges and projections that stand out, than in recesses, etc., a control of the plating on the fin elements may be effected by adjustment and control of the n spacing in the corrugated structure. Thus it has been found that, under average plating conditions, a fin spacing of approximately tive to seven fins per inch will achieve a suitable taper in the plating from a maximum on the outer surface of the connecting loop to substantially no plating at about the midpoint of the fins. As the number of ns per inch is increased, thus decreasing the space between adjacent tins, the amount of metal deposited on the face of the fin element will be reduced and conversely by decreasing the number of ns per inch and thereby opening the spacing, the amount of metal and extent thereof along the n face will be increased.

In the fabrication of serpentine or corrugated fin structures of relatively uniform thickness, particularly where intermeshing toothed forming wheels are employed, the ns as they emerge from the forming mechanism are normally disposed in angular relation with respect to one another, as indicated at M of FIG. 6, wherein the n spacing is at a maximum and only a few tins extend per inch. Usually, following the formation of the 1in structure, the corrugations of the ns are brought together by a suitable compressing action on the fin structure, as indicated at C of FIG. `6, which bends the crown portions. As the lin structure has inherent resiliency, the individual ns will subsequently separate slightly following release, but the separation will be substantially uniform along the structure. `Following such compaction, the fins then may be easily and precisely separated by bending the crown portions to the desired spacing, which normally will be greater than the spacing following such compaction, for example, as indicated at D in FIG. 6. In the practice of the present invention, the desired spacing of the fin elements, following their formation, would be controlled by the spacing desired during the plating operation to achieve a desired degree of plating With the particular variables employed in the plating operations.

It is probable that in some, if not most cases, following the plating operation, the n elements will be respaced from that employed in said plating operation to that desired in the ultimate fin structure, this being readily accomplished by further expansion of the structure, or, as indicated at C in FIG. 6, by suitable compaction, which may in some cases be followed by an additional nal sizing operation involving separation of the iin elements -to the ultimate spacing desired as indicated at F in FIG. 6.

As the variation in plating thickness would also tend to build up a greater thickness of plating metal adjacent the end edges of the lin elements, as compared with the laterally intermediate portions of the 1in elements, flow of plating solution into the end edges of the corrugations, except in special circumstances, will normally be restricted to such a Adegree as would tend to produce uniformity of plated material across the lin element. This may be accomplished by placing suitable restricting members adjacent the end edges of the fin structure and may advantageously be achieved in the plating apparatus by utilizif ing means formed on the conveyor structure which transports the fin material through the plating bath, to block off the ends of the corrugations.

FIG. 4 illustrates in semi-diagrammatic form an appa- 5 ratus for effecting the plating operation, in which the strip 1 is moved along a supporting conveyor structure, indicated generally by the numeral 4, through a plating solution contained in a suitable container 5, indicated generally by dotted lines. The conveyor illustrated com-y prises a pair of endless belts 6a and 6b, each carried on a respective pair of pulleys or drums 7, at least one drum of each pair being suitably powered whereby the opposed portions 8 of the belts will travel at the same speed in the same direction, such opposed portions of the belts being suitably backed by suitable means such as bars 9 over which the belts are slidable.

As illustrated in FIG. 5, each belt is provided with outwardly directed beads or flanges 11 between which the n structure 1 may be disposed for transport through the plating bath, the distance between the outer faces of the belts being approximately equal to, or slightly less than the corresponding length of each fin element 2 and preferably formed from a suitable semi-resilient material which will tend to suitably grip the end edges of the fin elements and adequately support the n structure in the plating bath, the beads 11 preventing vertical movemen-t of the fin structure during its travel, The backing plates 9 prevent outward movement of the portions 8 of the belts, eliminating the possibility of -the latter spreading and thereby insufficiently supporting the iin structure.

A plurality of anodes 12 may be suitably disposed Within the plating solution, as for example, as illustrated in FIG. 5, with at least one anode above and one below the corrugated strip 1 and suitably connected, by conductors 14 or the like, to one side of a source of plating current such as a battery 13. The opposite side of the current source 13 is operatively connected to the n structure 1 forming the plating cathode by suitable means such as contact assemblies indicated generally by the numeral 15 disposed at opposite ends of the respective n elements and embodying suitable endless contact members 16 mounted on rollers 17 which in turn are supported by carriages 18. The latter may be suitably supported in a fixed member 19 and resiliently urged toward and into engagement with the lin structure by suitable means such as springs 21 operative to maintain the contacts 16 in engagement with the end edges of the n structure. One or both of the contacts 16 may be operatively connected to the current source 13 by conductor means 22.

It will be appreciated that the apparatus above described is diagrammatically illustrative of the general construction of a plating device for practicing the invention and in actual practice the details and proportions would vary widely, depending upon the particular circumstances involved. The supporting and conveyor structure illustrated in FIG. 4 would in all probability be of considerable length and the belt structures could be so designed that they could be arranged in a serpentine fashion to derive greater length of travel through the plating solution. Likewise, such travel will depend to a large extent on the conditions surrounding the plating operation as to rate of travel through the bath, plating current, etc., and the ultimate design will therefore involve and take into consideration all of the variables concerned.

Upon completion of the tapered n structure as above described, it may be fabricated with the other elements of the heat exchanger, as for example, fluid tubes, platelike side walls of plate type exchangers, etc., in substantially the same manner as previous untapered serpentine structures.

It will be noted from the above description that I have developed a very simple method of producing a serpentine n structure having iin elements which taper crosssectionally, as well as provided a novel apparatus for,

producing such iin structures.

It also will be apparent that the present invention enables the production of a novel tapered n structure in which the manufacturing tolerances may be readily kept within satisfactory limits and eliminates cumulative tolerances such as might exist in fin structures employing mechanical means for deriving the tapered construction.

Having thus described my invention, it will be obvious that various immaterial modifications may be made in the same without departing from the spirit of my invention; hence I do not wish to be understood as limiting myself to the exact form, construction, arrangement and combination of parts herein shown and described, or uses mentioned.

What I claim as new and desire to secure by Letters Patent is:

1. The method of forming a serpentine fin structure comprising thickened arcuate crown portions and interconnecting intermediate portions, which interconnecting portions progressively taper to a lesser degree toward their intermediate section from said crown portion, comprising the steps of forming a strip of material, int-o a serpentine-shaped iin structure having a plurality of sub-v stantially uniform corrugations comprising crown portions and interconnecting intermediate portions, and passing said corrugated n structure through an electro-plating bath to selectively plate the outermost surfaces of said crown portions and intermediate portions to a greater extent than the corresponding innermost surfaces of each crown portion and interconnecting intermediate por-tions of the 1in elements, with the plating thickness varying from each crown portion toward the intermediate section of the interconnecting intermediate portions.

2. The method of forming a serpentine fin structure comprising thickened arcuate crown portions and interconnecting intermediate portions, which interconnecting portions progressively taper to a lesser degree toward their intermediate section from said crown portion, comprising the steps of forming a strip of material, into a serpentine-shaped iin structure having a plurality of corrugations comprising crown portions and interconnecting intermediate portions, and passing said corrugated fin structure through an electro-plating bath to selectively plate the outermost surfaces of said crown portions and intermediate portions to a greater extent than the corresponding innermost surfaces of each crown portion and interconnecting intermediate portions of the fin elements, with the plating thickness varying from each crown portion toward the intermediate section of the interconnecting intermediate portions.

3. The method of forming a serpentine fin structure comprising thickened arcuate crown portions and interconnecting intermediate portions, which interconnecting portions progressively taper to a lesser degree toward their intermediate section from said crown portion, comprising the steps of forming a strip of material of substantially uniform thickness into a serpentine-shaped n structure having a plurality of substantially uniform corrugations comprising crown portions and interconnecting intermediate portions, passing said corrugated n structure through an electro-plating bath for pla-ting the same material as that of the structure to selectively plate the outermost surfaces of said crown portions and in-termediate portions to a greater extent than the corresponding innermost surfaces of each crown portion and interconnecting intermediate portions of the n elements, with the plating thickness varying from each crown portion toward the intermediate section of the interconnecting intermediate portions, and simultaneously restricting the entry of plating liquid at lthe fin end edge of the iin elements to reduce excessive plating thereat.

4. The method of forming a serpentine n structure comprising thickened arcuate crown por-tions and interconnecting intermediate portions, which interconnecting portions progressively taper to a lesser degree toward their intermediate section from said crown portions, comprising the steps of forming a strip of material, of substantially uniform thickness, into a serpentine-shaped in structure having a plurality of substantially uniform corrugations comprising crown portions and interconnecting intermediate portions, bending said fin structure at the crown portion thereof to substantially close the same, bending said lin structure at the crown portions thereof to open the corrugations of the tin structure to a predetermined substantially uniform amount, and passing said corrugated fin structure through an electro-plating bath for plating the same material as that of lthe fin structure under conditions that will selectively plate the outermost surfaces of said crown portions and intermediate portions to a greater extent than the corresponding innermost surfaces of each crown portion and interconnecting intermediate portions of the n elements, with the plating thickness varying from each crown portion toward the intermediate section of the interconnecting intermediate portions.

5. The method of forming a serpentine fm Structure comprising thickened arcuate crown portions and interconnecting intermediate portions, which interconnecting portions progressively taper to a lesser degree toward their intermediate section from said crown portions, comprising the steps of forming a strip of material, of substantially uniform thickness, into a serpentine-shaped iin structure having a plurality of substantially uniform corrugations comprising crown portions and interconnecting intermediate portions, bending said n structure at the crown portion thereof to substantially close the same, bending said iin structure at the crown portions thereof to open .the corrugations of the fin structur-e to a predetermined substantially uniform amount, passing said corrugated fin structure through an electro-plating bath for plating the same material as that of the tin structure under conditions that will selectively plate the outermost surfaces of said crown portions and intermediate portions to a greater extent than the corresponding innermost surfaces of each crown portion and interconnecting intermediate portions of the fin elements, with the plating thickness varying from each crown portion toward the intermediate section of the interconnecting intermediate portions, rebending said n structure to reclose the corrugations, and reopening said corrugations to the ultimate fin spacing desired.

6. The method of forming a serpentine fin structure comprising thickened arcuate crown portions and interconnecting intermediate portions, which interconnecting portions progressively taper to a lesser degree toward their intermediate section from said crown portions, comprising the Steps of forming a strip of material, of substantially uniform thickness, into a serpentine-shaped fin structure having a plurality of substantially uniform corrugations comprising crown portions and interconnecting intermediate portions, bending said n structure at the crown portion thereof to provide a predetermined fin spacing, passing said corrugated fin structure through an electro-plating bath for plating the Same material as that of the iin structure under conditions that will selectively plate the outermost surfaces of said crown portions and intermediate portions to a greater extent than the corresponding innermost surfaces of each crown portion and interconnecting intermediate portions of the iin elements, with the plating thick-ness varying from each crown portion ltoward the intermediate section of the interconnecting intermediate portions, and rebending said corrugations to the ultimate fin spacing desired.

References Cited by the Examiner UNTED STATES PATENTS 1,151,777 8/1915 Fulton 29-480 1,648,046 ll/l927 Fulton.

(Gather references on following page) 7 UNITED STATES PATENTS Grupe 204-13 X Hall 20428 X Bowers 29-156.6 X

Barrett 29-157.3

Carlsen et a1. 29-157.3

Belaie 16S-146 Gier 165-185 Holm 165-185 Modine 29-157.3 10

8 FOREIGN PATENTS 608,557 9/1948 Great Britain.

JOHN F. CAMPBELL, Primary Examiner.

CHARLES SUKALO, WHITMORE A. WILTZ,

Examiners.

I. D. HOBART, Assistant Examiner. 

1. THE METHOD OF FORMING A SERPENTINE FIN STRUCTURED COMPRISING THICKENED ARCUATE CROWN PORTIONS AND INTERCONNECTING INTERMEDIATE PORTIONS, WHICH INTERCONNECTING PORTIONS PROGRESSIVELY TAPER TO A LESSER DEGREE TOWARD THEIR INTERMEDIATE SECTION FROM SAID CROWN PORTION, COMPRISING THE STEPS OF FORMING A STRIP OF MATERIAL, INTO A SERPENTINE-SHAPED FIN STRUCTURE HAVING A PLURALITY OF SUBSTANTIALLY UNIFORM CORRUGATIONS COMPRISING CROWN PORTIONS AND INTERCONNECTING INTERMEDIATE PORTIONS, AND PASSING SAID CORRUGATED FIN STRUCTURE THROUGH AN ELECTRO-PLATING BATH TO SELECTIVELY PLATE THE OUTERMOST SURFACES OF SAID CROWN PORTIONS AND INTERMEDIATE PORTIONS TO A GREATER EXTENT THAN THE CORRESPONDING INNERMOST SURFACES OF EACH CROWN PORTION AND INTERCONNECTING INTERMEDIATE PORTIONS OF THE FIN ELEMENTS, WITH THE PLATING THICKNESS VARYING FROM EACH CROWN PORTION TOWARD THE INTERMEDIATE SECTION OF THE INTERCONNECTING INTERMEDIATE PORTIONS. 